Panametrics GF868 DigitalFlow Flare Gas Ultrasonic Flowmeter

Overview

The Panametrics GF868 (DigitalFlow GF868) is a dedicated ultrasonic flowmeter for flare gas, vent gas and other difficult hydrocarbon gas streams. Flare headers carry mixtures from many sources at the same time, and their flow can swing from a near-stagnant purge to a full relief event in seconds, sometimes reversing direction. The Panametrics GF868 was engineered for exactly those conditions, combining wetted ultrasonic transducers, digital signal processing and a patented method of calculating the average molecular weight of the gas, so that operators obtain volumetric flow, standard volume and mass flow from one installation.

Seven Star LLC supplies the Panametrics GF868 and its transducer, preamplifier and insertion hardware to refineries, gas plants and production stations in the Sultanate of Oman and across the GCC, with engineering support in Muscat. Flare metering has become a priority for regional operators as flaring reduction and emissions reporting programmes tighten, and an ultrasonic flare meter is often the reference instrument used to quantify and reduce routine flaring.

Measurement Principle

Two transducers are installed through the pipe wall on a diagonal path. Each sends ultrasonic pulses to the other; the pulse travelling with the gas arrives sooner than the pulse travelling against it. The Panametrics GF868 applies its patented Correlation Transit-Time technique to these signals, cross-correlating the received waveforms to determine the time difference precisely even when the gas is noisy, wet or changing composition. From that difference and the path geometry the Panametrics GF868 computes velocity, and with temperature and pressure inputs it calculates standard volumetric flow.

The same measurement also yields the speed of sound in the gas. Combined with temperature and pressure, the on-board computer uses sound speed to calculate the instantaneous average molecular weight and, from it, mass flow. Panametrics states a standard bidirectional range of 0.03 to 100 m/s (0.1 to 328 ft/s) and an extended one-direction range to 120 m/s (394 ft/s), giving rangeability of 3280:1 standard and 4000:1 extended. Unlike thermal dispersion meters, the transit-time method does not depend on the heat transfer coefficient of the gas and has no moving parts to wear.

Engineering Design of the Panametrics GF868

A Panametrics GF868 system comprises a pair of transducers for each channel, in-line XAMP preamplifiers and an electronics console that can sit up to 300 m (1,000 ft) from the pipe. Transducers are installed in a flowcell or directly into an existing header by hot or cold tapping through 2 in or 3 in flange-mounted packing glands and valves. T5, T5MAX and T17 wetted transducers are made from titanium as standard, with Hastelloy, Monel or SS316 options, and cover process pressures from -2 to 1500 psig. The T17 is offered in temperature classes from -220 °C up to 300 °C for cryogenic and hot services.

The standard console is an epoxy-coated aluminium Type 4X/IP66 enclosure, with stainless steel and explosion-proof versions; the flameproof option carries Ex d IIC T6 Gb under IECEx and ATEX. Six 4-20 mA outputs, two 4-20 mA inputs for pressure and temperature transmitters, RS232 and optional RS485, HART 7, Modbus RS485 or TCP/IP, Ethernet, OPC server and Foundation Fieldbus are available, together with four slots for extra analogue, RTD, totalizer and relay boards.

Key Features

The Panametrics GF868 brings together measurement and diagnostic functions that flare engineers rely on:

• Velocity, volumetric, standard volumetric and mass flow from one meter, with built-in totalizers.
• Patented average molecular weight calculation that extends range and compensates for non-hydrocarbon gases.
• Turndown of 3280:1 standard and 4000:1 in the Extended Range version.
• Optional net heating value (NHV) output in BTU/SCF, MJ/m³ or kJ/m³ for combustion and assist-steam control.
• Daily self-calibration health check that reports PASS or FAIL at a time chosen by the operator.
• One-path or two-path configurations; two paths improve accuracy or can measure two separate pipes.
• Applicable to pipes from 2 in to 120 in (50 mm to 3 m) in diameter.
• Data logging of more than 43,000 points and two backlit graphic displays with a 39-key keypad.

Industrial Applications

The principal duty of the Panametrics GF868 is flare gas measurement on refinery, petrochemical, gas processing and offshore flare headers, where operators must report flared volumes, identify leaking relief valves and control steam injection at the flare tip. A rise in flow accompanied by a shift in molecular weight helps locate which unit is leaking into the system, and the mass flow signal supports plant mass balance. Panametrics also lists vent gas, hydrocarbon gases, biogas and digester gas as suitable services, making the Panametrics GF868 relevant to wastewater treatment and landfill gas sites as well as oil and gas.

In Oman, typical installations include flare and vent headers at gas processing plants, refinery complexes in Sohar and Duqm and oil gathering stations operated under flaring reduction targets. Seven Star LLC supplies complete Panametrics GF868 packages with Muscat engineering support for transducer and path selection. For general-purpose process gas metering the Panametrics DigitalFlow GM868 gas flowmeter is an alternative, while sites that also monitor gas quality often add a Panametrics HygroPro II moisture transmitter or a AMETEK 5100P TDLAS analyzer.

Technical Specifications

Selected Panametrics GF868 data from datasheet PANA015DS Rev. 20:

How to Order

For a quotation on the Panametrics GF868, share the flare line size, gas composition range, pressure, temperature, hazardous area classification and whether you need one or two paths or the NHV option. Seven Star LLC will prepare a configuration with availability and lead time confirmed at quotation and engineering support from Muscat for customers in Oman and the GCC. The full datasheet can be downloaded from this page.